Control system



Feb. 6, 1934. AHOEKE 1,946,282

CONTROL SYSTEM Filed Aug. 3,1932

Inventor": Fred AHOeKe,

bWM/M His Attorney.

Patented Feb. 6, 1934 PATENT OFFICE CONTROL SYSTEM Fred A. Hoeke, Homewood, Ala., assignor to General Electric Company, a corporation of New York Application-August 3, 1932. Serial No. 627,337

10 Claims.

This invention relates to control systems, more particularly to systems for controlling the operation of steel mill tilting tables and the like, and it has for an object the provision of a simple, re-

liable, eflicient and inexpensive system of this character.

More specifically the invention relates to steel rolling mills of the vertical three-roll type in which the strip is passed from a stationary table between the middle roll and one of the outside rolls to a. receiving table which is then tilted to such a position that the strip may be passed back to the stationary table between the middle roll and the remaining outside roll, and a specific ob-' ject of the invention is the provision of means for automatically controlling the elevating and lowering operations of the table, eliminating all 3 3 gation of the strip with each pass to prevent operation of the table operating mechanism until the trailing end of the strip reaches predetermined positions both after the delivery of the strip from the rolls to the-tilting table and after the res. delivery of the strip from the table to the rolls. In carrying the invention into effect in one form thereof, means are provided for operating the table and light sensitive means controlled by .the strip are provided for controlling the table operating means to elevate the table after the strip is delivered from the rolls to the table together with means controlled by operation of the table for cooperating with the light sensitive means to effect lowering of the table when the.

- strip is returned from the table to the roll. In

one embodiment of the invention the table operating means is controlled by electromagnetic switching mechanism under the control of the light sensitive means and is arranged to effect elevation of the table when the trailing end of the strip is ina predetermined position after delivery from the rolls to the table and additional switching means controlled by operation of the table operating means cooperate with the light sensitive means and the electromagnetic switching means to effect lowering of the table when the trailing end of the strip is in a predetermined position upon redelivery of the strip from the table to'the rolls. I

For a better and more complete understanding of my invention reference should now be had to the following specification and to theaccompanying drawing, the single figure of which is a diagrammatic representation of an embodiment 55 of the invention.

Referring now to the drawing, -a strip or sheet of material 10, such, for example, as a strip of steel, is passed from a stationary table 11 between the middle and lower rolls of the three vertical rolls 12, 13, 14; to a receiving table 15 so during which operation the gage of the strip is reduced. After the strip has been delivered from the rolls 12, 13 to the table 15, the latter is elevated from the horizontal position in which it is shown to the tilted position illustrated in dotted 66 lines and the strip 10 is passed back between the rolls 13, 14 to the stationary table 11 during which rolling operation the gage of the strip is still fur- 1 ther reduced. This cycle is repeated until the strip has passed the required number of passes 70 through the mill after which the strip is delivered to a continuous running conveyor or stacker.

The receiving table 15 is raised and lowered between the horizontal position in which it is shown and the tilted position illustrated in dotted lines by any suitable means such for example as the hydraulic operating. device 16. Briefly this device comprises an outer wall 1'7 defining a liquid retaining chamber partly broken away to reveal the internal operating mechanism. A suitable so liquid, such for example as oil 18, is contained within the chamber. Withinthe chamber there is also provided a piston 19 which is mechanically connected to the tilting table "15 by means of the uprights 20 and 21 and the connecting rod 22. The bottom wall of the liquid containing chamber is formed as illustrated with an upwardly projecting central portion upon which rests the lower face of the piston 19 thereby providing an annular liquid containing chamber between .the lower face of the piston and the upper face pressure on the under side of thepiston, and'100 causing the latter to rise with the splined upright 23 and thereby elevate the table 15. .The impeller within the piston 19 is rotatediby any suitable means, such for example as the electric motor 24 which is illustrated mounted. externally of the upper side of the containing wall 1'7. It will thus be seen that when the impeller within the piston 19 is rotated by the electric motor 24 that a liquid pressure is built up against the underneath face of the piston, which pressure conmum tinues as long as the rotation of the motor continues. Accordingly, when the motor is rotated the table 15 is elevated to the dotted position and remains in this position as long as the rotation of the motor continues and when the rotation of the motor ceases the liquid pressure against the underneath face of the piston disappears and the piston 19 and the table 15 both descend to the lower position in which they are illustrated in the drawing.

The operation of the driving motor 24 of the hydraulic operating device 16 is controlled by a suitable electromagnetic switching device 25 illustrated as a contactor provided with an operating coil 26, upper contact 27 for controlling the circuit of the motor 24 and lower contactor 28 for establishing aholding circuit for the operat ing coil 26. The operating call 26 is wound for less than normal voltage so that it is completely energized when connected across a standard supply source with the resistance 26a in series relation therewith.

The operation of the contactor 25 to deenergize the motor 24 is in turn controlled by suitable electromagnetic switching mechanism illustrated as contactors 29 and 30, the operation of the latter of which is in turn controlled by suitable light sensitive means illustrated as a photoelectric cell 31 and a cooperating light source illustrated as an incandescent lamp 32. The photoelectric cell 31 is connected in circuit with the operating winding 33 of contactor 30 and a suitable amplifying device 34 is included in the connections to which power is supplied from any suitable source such for example as that represented by the two supply lines 35.

As shown, the photoelectric cell 31 is arranged on the tilting table side of the rolls 12, 13, 14 in such a manner that when no strip of material is on the table 15, a beam of light from the lamp 32 is transmitted through the table and falls upon the light sensitive element of the photo cell 31. The circuit arrangement in which the photo cell 31 is connected is so designed that when light from the lamp 32 falls upon the photo cell the operating coil 33 of the contactor 30 is deenergized and the contacts occupy the position in which they are illustrated whilst when the light beam from the lamp 32 to the photo cell 31 is interrupted the operating coil 33 isenergized and the contacts of the contactor are operated to their upper position.

As shown, the contactor 30 is provided with an upper contact 36 which in its upper position serves to establish an energizing circuit for the operating coil 37 of contactor 29 and is also provided with a lower contact ,38 which cooperates with the lower contacts 39 of contactor 29 to establish an energizing circuit for the operating coil 26 of contactor 25.

A suitable switching device 40 illustrated as a limit switch operated by the tilting table 15 cooperates with the upper contact 36 of the contactor 30 and with upper contact 41 of contactor 29 to deenergize the operating coil 26 of contactor 25. The limitswitch 40 may be of any suitable type and it is also to be understood that instead of being operated directly by the table 15 as shown. it may be operated by the table operating mechanism in accordance with the movement of the table. Witli the above understanding of the apparatus andfconnections comprising an embodiment of the invention, the operation of the system will be readily understood from the following detailed description.

The table 11 is provided with a chain 42 driven by any suitable means such for example as an electric motor (not shown) and advances the strip 10 between the rolls 12, 13 by means of which the gage of the strip is reduced. As the leading edge of the strip emerges from between the rolls 12, 13 and advances over the table 15, it interrupts the beam of light from the lamp 32 to the photo cell 31 thereby energizing the operating coil 33 of contactor 30. In response to the energization of its operating coil, the upper contact 36 of contactor 30 establishes an energizing circuit for the operating coil 37 of contactor 29 that is traced from the upper side of the supply source 43 through the operating coil 37, upper contact 36 in the upper position thereof and thence by conductor 44 to the lower side of the supply source 43. .Contactor 29 closes both its upper and lower contacts in response to the energization of its operating coils but at this time these contacts do not establish any controlling circuits since it will be observed that any circuits that might be completed are open at the contacts 36 and 38 of contactor 30. As the rolling process of the strip 10 continues the trailing edge of the strip finally emerges from between the rolls 12, 13 and is delivered to the table 15 so that the light beam from the lamp 3-2 to the photo cell 31 is reestablished thereby deenergizing the operating coil 33 of the contactor 30, the contacts of which descend under the attraction of gravity to the lower position in which they are illustrated. The upper contact 36 in descending fromits upper to its lower position interrupts the energizing circuit for the operating coil 3'7 of the con- 1m tactor 29, but due to the fact that the contactor 29 is provided with a time delay device illustrated as adash pct 45, the contacts 39 and 41 remain in engagement with their cooperating stationary contacts for a predetermined interval of time that is determined by the setting of the dash pot. As a result of this time delay feature in the operation of the contactor 29, the lower movable contact 39 remains in engagement with its cooperat ing stationary contacts after the lower movable m contact 38 of the contactor 30 has descended into engagement with its cooperating stationary contacts thereby establishing an energizing circuit for the operating coil 26 of contactor 25 that is traced from the upper side of the supply source 43 through the resistance 26a, operating coil 26, conductor 46, lower contact 38 in the lower position thereof, lower contact 39 in the upper position thereof to the lower side of the supply source 43.

The contactor 25 in responding to the energization of its operating coil moves to the upper or closed position in which its upper movable contact 2'7 connects the motor 24 of the hydraulic operating device 16 to the supply source 43 over a n5 circuit that is traced from the upper side of the supply source 43 through upper contact 27 in the closed position thereof, conductor 4'7, motor 24 and thence by conductor 43 to the lower side of the supply source 43.

Energlzation of the motor 24' effects rotation of -the pump impeller within the piston 19 thereby building up a liquid pressure againstthe lower face of the piston 19 causing the latter to rise and elevate the tilting table 15 to the tilted position illustrated in dotted lines. After a predetermined interval of time determined by the setting of the dash pot 45, the contacts 41 and 39 of contactor 29 descend to the lower open position in which they are illustrated but contact 39 in opening no "for the operating coil 37 o! contactor 29.

does not interrupt the energizing circuit for the operating coil 26 of contactor 25 which is maintained by the holding circuit independently of contact 39 by means or the contact 28.

It will be observed that the tilting table 15 is also provided with a driving chain 49 which is automatically reversed by any suitable means (not shown) a predetermined time interval after the trailing end of the strip permits the light beam from the lamp 32 to the photo cell 31 to be reestablished.

The strip 10 is now delivered to the middle and upper rolls 13. 14 by means oi which its gage is still further reduced. As the leading edge of the strip (which was iormerly the trailing edge) interrupts the light beam from the lamp 32 to the photo cell 31, the operating coil 33 of contactor 30 is again energized and the contactor is again operated to its upper position in which its upper movable contact 36 reestablishes the energizing circuit for the operating coll 3'7 01 contactor 29. The contactor 29 is again operated to its upper or closed position in response to the energizatlon of its operating coll but as before no controlling circuits are established at this point since any circuits that might be established by the contacts or contactor 29 are open at the contacts of the contactor 30 as shown. However, as the trailing edge of the strip leaves the table 15 and permits the light beam from the lamp 32 to the photo cell 31 to be reestablished the operating coil 33 of contactor 30 is again deenergized permitting its movable contacts to descend under the attraction of gravity to the lower position in which they are illustrated. The upper contact 36 in moving out of engagement with its cooperating upper stationary contact interrupts the energizing circuit Due however to the time delay feature in the operation of contactor 29, the upper contact 41 remains in engagement with its cooperating stationary contacts until alter the movable contact 36 has descended into engagement with its lower cooperating stationary contacts thereby cooperating with the limit switch 40 to short circuit the operating coil 26 of contactor 25. This short circuit is traced from the upper terminal 01 the coil 28 by conductor 50, upper contact 41 in the closed position thereof, upper contact 36' in the lower position thereof, conductor 51, limit switch 40 in the. closed position thereof, and thence by conductors 52 and 46 to the lower terminal of operating coil 26.

The short circuit about the operating coil 26 results in its deenergization thereby permitting the movable contacts 27 and 28 of contactor 25 to descend under the attraction of gravity to the lower position in which they are illustrated.

Contactor 27 in its open position interrupts the supply circuit for motor 24 the rotation of which thereupon ceases and thereby decreasing the liquid pressure on the lower face of the piston 19 which in turn causes the piston 19 and the table 15 connected thereto to descend under the attraction of gravity to the position in which they It will be observed from the above-described operation that the elevating operation of the table 15 is not initiated until the trailing edgqpt the strip 10 emerges from between the rolls 12, 13 and permits the light beam from the lamp 32 to the photo cell 31 to-be reestablished and likewise it will be observed that the lowering operation of the table 15 is not initiated until the trailing edge 01. the strip 10 has left the table 15 as it is redelivered to the rolls. It will thus be clear that due to the arrangement of the light sensitive means and the arrangement or the interlocking control circuits of the electromagnetic switching mechanism compensation is made for the elongation of the strip resulting from each pass through the rolls.

Although in accordance with the provision of the patent statutes, I have described this invention as embodied in concrete form, it is to be understood that the apparatus and circuit connections shown in the drawing are merely illustrative and the invention is not limited thereto since alterations andmod'ifications will readily suggest themselves to persons skilled in the art without departing from the true spirit oi. the invention or the scope of the annexed claims.

What'I claim as new and desire to secure by I Letters Patent of the United States, is,-

1. A control system for a tilting table operating upon a strip of material comprising means for operating the table, a single light sensitive device controlled by. the passage 01 the strip in one direction for causing said operating means to elevate the table, and means controlled by operationof the tableand cooperating with said lit light sensitive device for causing said operating means to lower said table in response to the passage of said strip in 'the reverse direction.

2. A control system for a tilting table operating upon a strip of material comprising means for operating the table, a single light sensitive device controlled by the passage of the strip in one direction and switching means controlled by said light sensitive device for controlling said operating means to elevate the table, and a switching device controlled by. operation of said table and cooperating with said light sensitive device for controlling said operating means to lower said table in response to passage of said strip in the reverse direction. I25

3. A control system tor tilting tables operating on a strip oi material comprising an hydraulic device for operating the table, a single light sensitive device controlled by passage of the strip in one direction for energizing said hydraulic device to elevate the table, and limit switch mechanism operable in a predetermined position of the table and cooperating with said light sensitive device to deenergize said hydraulic device to lower said table upon passage or said strip in the reverse direction.

4. In a steel mill having rolls and a cooperating tilting table for passing a strip back and iorth between the rolls, means for operating the table, a single light sensitive device controlled by the strip, and means controlled by said light sensitive device for controlling said table operating means to elevate the table when the trailing end or the strip is in a predetermined position after passage of the strip through the rolls to the table and for 145 controlling said table operating means to lower the table when the trailing end or the strip is in a predetermined position upon passage or the strip from the table to said rolls.

5. In a steel mill having rolls and a cooperating 160 tilting table for passing a strip back and forth through the rolls, means for operating the table, a single light sensitive device controlled by the strip and electromagnetic switching means controlled by said light sensitive device for controlling said table operating means to elevate the table when the trailing end of the strip reaches a predetermined position after passage of the strip through the rolls to the table, and a switching device controlled by operation of the table operating means and cooperating with said light sensitive device and switching means for controlling said table operating means to lower the table when the trailing end of the strip is in a predetermined position upon return passage of said strip from the table to said rolls.

6. A control system for tilting tables operating on a strip of material comprising means for operating the table, a switching device for controlling said operating means, light sensitive means controlled by the strip and a second switching device controlled by said light sensitive means for controlling said second contactor, a third contactor controlled by said second contactor and cooperating therewith to control said first contactor to cause said operating means to elevate the table, and limit switch mechanism operable in a predetermined position of said table and cooperating with said second and third contactors for controlling said first contactor to cause said table operating means to lower said table.

8. In a steel mill having rolls and a cooperating tilting table for passing a strip back and forth through the rolls, a control system comprising means for operating the table, an electromagnetic switching device for controlling the operation of said table operating means, a second electromagnetic switching device, light sensitive means responsive to passage of the leading edge of the strip for actuating said second device to a first position and responsive to passage of the trailing edge of the strip for operating said secmagnetic switching device responsive to actua tion of said second device to said first position for partially completing an energizing circuit for said first switching device and provided with a time element device so that upon operation of said second device to said second position said energizing circuit is completed to eflfect elevation of the table.

9. In a steel mill having rolls and a cooperating tilting table for passing a strip back and forth between the rolls, an hydraulic device for operating the table, an electromagnetic contactor for controlling said hydraulic device, a limit switch controlled by operation of said hydraulic device, light sensitive means controlled by the strip and second electromagnetic contactor controlled by said light sensitive means, a contactor controlled by said second contactor and provided with a time delay device for cooperating with said second contactor when the strip is passed through the rolls to said table to energize said first contactor to elevate the table and or cooperating with said second contactor and said limit switch to deenergize said first contactor and thereby lower the table upon passage oi the strip from the table through the rolls.

10. In a steel mill having rolls and a cooperating tilting table for passing a strip back and forth through the rolls, a control system comprising means for operating the table, an electromagnetic switching device for controlling the operation of said table operating means, a second electromagnetic switching device, light sensitive means responsive to passage of the leading edge of the strip for actuating said second device to a first position and responsive to passage of the trailing edge of the strip for operating said second device to a second position, a third electromagnetic switching device responsive to actuation of said second device to said first position for partially completing an energizing circuit for said first switching device and provided with a time element device for eflecting cooperation of said third switching device with said second switching device upon passage of the trailing edge of the strip to complete the energizing circuit and effect elevation of the table, and a limit switch operable in the elevated position of the table for cooperating with said second and third switching device upon a subsequent passage of the trailing edge of the strip for deenergizing said first switching device to effect lowering of the table.

FRED A. HOEKE.

- ond device to a second position, a third electrov 

